This invention relates to braking systems, in more particular, to brake control systems adapted to engage the brakes of a towed vehicles when the brakes of the towing vehicle are actuated so as to causes the brakes of the towed vehicle to assist the brakes of the towing vehicle in stopping the two vehicles. There are a number of patents and designs for braking systems intended to be employed with one vehicle being towed by another. When a vehicle is being towed by another vehicle, the braking system of the towing vehicle must function to stop both the towing vehicle and the towed vehicle, unless some auxiliary braking control is provided. The extra force of the towed vehicle on the braking system of the towing vehicle requires extra stopping distance and extra stopping time for the two vehicles. The extra weight of the towed vehicle also accelerates the wear and tear of the braking system of the towing vehicle thus increasing the frequency of repairs.
It has long been known that it is possible to provide a system that applies braking force to the towed vehicle in response to brake actuation in the towing vehicle. Trailers of various size and shape, intended for towing by a towing vehicle conventionally include brake systems that are either hydraulically or electrically operated. A number of prior art devices are intended to operate with the towed vehicle braking system. While these prior art devices are acceptable for their intended purposes, they have not solved a number of problems associated with towing a second vehicle. In particular, these systems generally do not function to cause the braking system of the towed vehicle to operate as quickly as is desirable in braking situations. In addition, the prior art designs do not function properly in a number of specific operating situations. Prior art systems in which we are aware of do not engage the brakes of the towed vehicle during backing up of the two vehicles. This can be especially important, for example, in situations in which the towed vehicle is a boat type trailer and it is desired to back the trailer down an extended boat ramp.
In general, there are two types of braking systems available for trailers. Legal requirement specify that all trailers that require brakes have means for activating the trailer brakes under trailer breakaway conditions. In hydraulic surge brake systems this is normally done by means of a cable or chain which is connected to the tow vehicle. Under trailer breakaway conditions, the connecting link is designed to provided mechanical activation of the master cylinder, and to maintain brake system operation as the trailer stops. If the trailer has an electric brake system, the emergency breakaway regulations require that the trailer be provided with an emergency battery back-up system that will provide electrical power to the brake magnets during trailer breakaways. In an electric breakaway system there is a breakaway switch with a pull pin and cable which, when attached to the tow vehicle provides electrical activation of the trailer brakes if the trailer disconnects from the tow vehicle during highway travel, for example. The components for this system are normally packaged as an emergency breakaway kit which has a battery and charger, emergency switch, and battery case in one package.
Hydraulic surge brakes are a totally trailer self-contained braking system, requiring no electrical, hydraulic or other connection of brake sensing components to the towed vehicle for automatic operation of the trailer brakes. In a hydraulic surge brake system, the differential pressure developed between the towing vehicle and the trailer, during the braking process, creates a mechanical pressure which is applied to the push rod of the master cylinder in a hydraulic surge brake coupler. This mechanical pressure is proportional to the difference in pressure between the two vehicles and therefore, the hydraulic output of the brake coupler, and resulting brake operation, is automatic, regulated, and proportional to the amount of braking being applied by the towing vehicle.
These various systems, though effective, are not without hidden problems. For example, the hydraulic surge brake system requires a certain amount of forward pressure to be effective. Backing a trailer up a hill puts pressure on the system and actuates the trailer brakes when the brakes are least needed. Backing a surge system down a hill takes away pressure and the trailer free wheels, leaving no chance of brake activation. Electric brakes work well in dry conditions, however, electric brakes are not recommended for boat trailers.
The brake control system of the present invention is intended for application with surge brake systems to increase their efficiency. Certain components of the system also can be applied to electrical brake systems to improve their operation. A particularly hazardous condition can exist with respect to rental trailers which are attached to a tow vehicle without really evaluating the safety features, and particularly the brake features of the vehicle being towed. In one embodiment of the invention, the braking system is self-contained and is installed on the towed vehicle, requiring only an interconnection to the brake light system of the towing vehicle for operation. Other embodiments of invention include a hard wire system intended for use with a single towing vehicle and trailer, for example, in the common recreational use of the system.
In view of the foregoing, as an object of the present invention to provide a brake control system that selectively actuates and deactuates the brake system of a towed vehicle in response to the activation and unactivation of the brake system of a towing vehicle.
Another object of the present invention is to provide an auxiliary brake system that actuates and deactuates the brake system of a towed vehicle in response to an electric signal that is carried from the towing vehicle to the towed vehicle.
Still another object of the present is to provide a brake control system that uses the existing brakes and/or brake lines of the towed vehicle.
A further object of the present invention is to provide a brake control system that uses a hydrostatic pump to apply pressure to the existing brakes and brake lines of the towed vehicle to create braking forces.
Still a further object of the present invention is to provide an auxiliary brake actuator that may be easily retrofit on a variety of vehicles that are typically towed behind another vehicle.
Another object of this invention is to provide a brake control system which, in one exemplary design, is self-contained and is installed on the towed vehicle.
Yet another object of this invention is to provide a brake control system that is microprocessor controlled.
Another object of the present invention is to provide a brake control system that is of relatively simple construction, which achieves the stated objectives in a simple effective and inexpensive manner, and which solves the problems associated with known braking systems employed with towed vehicles.
In accordance with this invention, generally stated, a brake control system has a microprocessor control adapted for use in a variety of applications. In one embodiment, the system is self-contained and is intended for attachment to the towed vehicle, the towed vehicle having a hydraulic brake system. The control includes a motor driven hydrostatic pump. The motor and pump are attached to a reservoir of brake fluid and the unit is attached to the hydraulic system of the towed vehicle. A battery provides power to the motor. A microprocessor controls application of electrical energy to the pump motor, and controls charging current to the battery. Other embodiments of the invention distribute the components of the control system between the towing vehicle and the towed vehicle.